Blast-furnace bell hopper with abrasion-resistant interior and method of construction



Sept. 14, 1965 s, COLLIER 3,205,181

BLAST-FURNACE BELL HOPPER WITH ABRASION-RESISTANT INTERIOR AND METHOD OF CONSTRUCTION Filed June 18. 1963 N R R 20 FIE- 2- l2 1 l6 t l8 l4 i a z llVVE/VTOR. '9 HHHHHHHM 1.1.11.9 EDWARD COLL/ER Attorney United States Patent 3,206,181 BLAST-FURNACE BELL HOPPER WITH ABRA- SION-RESISTANT INTERIOR AND METHOD OF CONSTRUCTION Edward S. Collier, North Huntington Township, Westmoreland County, Pa., assignor to United States Steel Corporation, a corporation of New Jersey Filed June 18,1963, Ser. No. 288,748 2 Claims. (Cl. 266-27) The present invention relates generally to blast furnaces and, more particularly, has .as its primary object the provision of a novel blast-furnace bell hopper having an improved abrasion-resistant surface on the interior wall thereof.

It is a more specialized object of my invention to provide a novel blast-fnrnace bell hopper having an improved abrasion-resistant surface on the interior wall thereof consisting of welded parallel beads of hard metal extending lengthwise of the hopper.

It is a further object of my invention to provide a method of forming an improved abrasion-resistant surface on the interior of a blas=t-furnace bell hopper.

The charging mechanism in the .top of a blast furnace conventionally includes a receiving hopper, a small-bell hopper or distributor, a small bell, a large-bell hopper, and a large bell. In operation, raw materials are carried to the top of the furnace by skip cars and dumped into the receiving hopper from whence they drop into the small-bell hopper. After a predetermined amount of raw material has accumulated in the small-bell hopper, the small bell is lowered from the bottom of its hopper to permit the raw material to drop into the large-bell hopper. After the raw material has dro ped into the large-bell hopper, the small bell is again raised to seal the bottom of the small-bell hopper. The large bell is then lowered at intervals to drop the raw material into the furnace from the large-bell hopper.

In order to improve productivity, many blast furnaces today are charged with beneficiated or concentrated materials or burdens and are operated with relatively high toppressures. The increasing use of beneficiated burdens and high top-pressures has created problems caused by the highly abrasive nature of beneficiated burdens and their wearing action on the interior walls of blast-furnace largebell hoppers. This wearing action causes premature deterioration of the large ball hopper interior in general, and the bell seat portion of the hopper in particular, so that it becomes increasingly difiicult to maintain the tight seal between the large bell and large-bell hopper necessary to prevent loss of gas from the blast furnace when it is operating at high top-pressures.

To protect the large-bell hopper from the damaging effects of the abrasive action of the beneficiated burdens and consequent gas-seal difiiculties, the interior walls and bell seat portion of the large-bell hopper are provided with an abrasion-resistant protective surface. However, all of such abrasion-resistant surfaces with which I am familiar provided protection for only a relatively short time before difiiculty was encountered in maintaining an effective gas-tight seal between the large-bell hopper and the large bell under high top-pressure conditions.

Abrasion-resistant surfaces applied to large-bell hoppers prior to my invention tended to develop numerous cracks extending lengthwise of the hopper in a relatively short time after the hopper was put in use. As these cracks developed in the surface of the bell seat portion of the hopper, they permitted the gases to escape from the furnace in ever-increasing amounts so that in a relatively short time the desired toppressure could not be maintained. Solid particles in the leaking gas which were 3,206,181 Patented Sept. 14, 1965 ICC picked up from the burden channeled and enlarged the cracks so that the gas-seal problem was further aggravated. After the cracks developed to such an extent that the furnace could no longer be operated at high top-pressures, it was necessary to discontinue operation of the furnace so that the bell seat port-ion of the hopper could be resurfaced. This, of course, detrimentally affected operat ing costs.

The aforementioned and other objects will become more apparent after referring to the following specification and attached drawing, in which:

FIGURE 1 is a sectional view in elevation of a blast furnace having the hopper of the invention installed therein;

FIGURE 2 is an enlarged vertical sectional view of the hopper of the invention; and

FIGURE 3 is an enlarged fragmentary view in vertical section of the hopper of the invention.

Referring more particularly to the drawing, reference numeral 2 designates, generally, the charging mechanism of a blast furnace 4. The mechanism 2, which includes a receiving hopper 6, a small-bell hopper 8, a small bell 10, a large-bell hopper 12, and a large bell 14, functions to charge raw material into the furnace in the conventional manner described hereiubefore.

The large-bell hopper 12 is constructed in accordance with my invention and consists of a one-piece, generally cylindrical casting which is provided with a protective abrasion-resistant hard metal surface 16 on its interior. The surface 16 of the invention consists of closely-spaced ridges 18 of hard, abrasion-resistant metal extending longitudinally from the bottom edge of the hopper to a point short of the upper edge thereof.

The portion of the protective surface 16 covering the lower area 20 of the hopper is machinable and is preferably of the following composition:

All percentages being by weight.

The portion of the surface 16 covering the interior of the upper area 21 of hopper 12 is non-machinable and is preferably of the following composition:

Percent Carbon 1.4 Manganese 3.0 Silicon 1.5 Chromium 22.0 Iron 72.1

All percentages being by weight.

The surface 16 is applied to the interior of the hopper 12 before the hopper is installed on the blast furnace and is formed by welding the machinable metal onto the lower portion 20 and the non-machinable metal onto the upper portion 21 of the hopper. The metal applied to the bell seat portion 22 of the hopper is machinable and is applied in a suflicient amount so that it can be ground smooth after welding to provide an effective gas-seal between the large bell and bell seat portion.

During welding of the respective metals on the interior of the hopper, it is essential that the weld beads which form the ridges 18 :be laid continuously on the respective portions of the hopper extending lengthwise thereof for reasons which will become apparent hereinafter.

Characteristically, as the weld beads cool after Welding, they will shrink longitudinally and as such shrink-age occurs, some transverse cracks will almost inevitably form in the weld beads. During handling of the hopper, strains in the casting are created which extend normal to the longitudinal axis of the hopper due to its bulk and cylindrical shape. These strains will also cause transverse cracks to occur in the weld beads. Since the beads of the weld metal of the protective surface 16 of my invention extend longitudinally of the hopper, any transverse cracks therein caused by shrinking of the weld beads or strains in the casting will extend normal to the longitudinal axis of the hopper and, therefore, will not form passages for gas to escape from the furnace.

Although grinding of the protective surface 16 on the bell seat portion 22 after Welding provides an initiallysmooth surface free of cracks, any previously existing cracks in the weld metal would cause lines of weakness in the ground surface coincident with the previously-existing cracks. However, such lines of weakness would extend normal to the longitudinal axis of the hopper as did the previously-existing cracks and, therefore, any cracks in this portion of the protective surface that would form along the lines of weakness would also extend normal to the longitudinal axis of the hopper and thus not interfere with positive sealing between the hopper and the bell.

The longitudinally directed weld beads of the protective surface 16 also render the surface less susceptible to damage from imp-act and erosion by the raw materials being charged into the furnace since the weld beads extend in the same direction the material is traveling. If

4 cracks in the beads are caused by impact of the raw materials, the cracks will extend normal to the longitudinal axis of the hopper and, therefore, will not form passages permitting gas to escape.

While one embodiment of my invention has been shown and described, it will be apparent that other adaptations and modifications may be made Without departing from the scope of the following claims.

I claim:

1. A method of forming an abrasion-resistant surface on the interior Wall of a blast-furnace bell hopper and the like which comprises welding a plurality of parallel juxtaposed beads of hard metal on said interior Wall extending longitudinally of said hopper.

2. A blast-furnace bell hopper comprising a generally cylindrical casting having an abrasion-resistant interior surface, said surface being composed of a plurality of parallel juxtaposed elongated ridges of Weld metal laid longitudinally of and Welded to the inner surface of said casting.

References Cited by the Examiner UNITED STATES PATENTS 12/41 Wingenroth 266-27 X 10/49 Mohr et a1. 

2. A BLAS-FURNACE BELL HOPPER COMPRISING A GENERALLY CYLINDRICAL CASTING HAVING AN ABRASION-RESISTANT INTERIOR SURFACE, SAID SURFACE BEING COMPOSED OF A PLURALITY OF PARALLEL JUXTAPOSED ELONGATED RIDGES OF WELD METAL LAID LONGITUDINALLY OF AND WELDED TO THE INNER SURFACE OF SAID CASTING. 